Ultrasonic Machining (USM)

Ultrasonic machining (USM) is a subtractive assembling measure that eliminates material from the outer layer of a section through high frequency , low amplitude vibrations of a tool against the material surface within the sight of fine rough particles.
USM is most normally used to machining of glass, ceramics, zirconia, valuable stones, and solidified prepares. USM permits the cutting of perplexing and non-uniform shape with very high accuracy.

1. Amlan Talukdar 1902007, M1 Department of Mechanical Engineering Date - 01.09.2021 ULTRASONIC MACHINING (USM)

2. OUTLINE Introduction Parts Working principle Process parameters Material removal mechanisms Advantages and Limitations Applications Conclusion References

3. Ultrasonic machining is a non-conventional machining process in which the abrasives hits on the work piece to remove the material. Ultrasonic machining (USM) is a mechanical material removal process used to erode holes and cavities in hard or brittle workpieces by using shaped tools, high-frequency mechanical motion and an abrasive slurry. This process is non-thermal, non-chemical, non-electrical and creates no change in the metallurgical, chemical or physical properties of the workpiece material. It can be used for machining both electrically conductive and non-conductive materials . INTRODUCTION (1,4)

4. PARTS (3)

5. The Ultrasonic Machin ing consists of different parts as follows: (3) Power supply - To starts, the machining process power is required. Transducer (electro-mechanical ) - converts an electrical signal to a mechanical signal whereas electromechanical transducer used to generates mechanical vibration. Horn or Concentrator - mechanically amplifies the vibration to the required amplitude and accommodates the tool at its tip. Tool - should be designed as like when the operation is performed does not lead to brittle fracture of it. Abrasive slurry - A water-based slurry of abrasive particle used as an abrasive slurry in this machining. ( Aluminum oxide, Silicon carbide ) Abrasive gun - supply an abrasive slurry, which is a mixture of abrasive grain and the water in between tool-workpiece interface under a definite pressure. Workpiece - perform several techniques like machining very precise and intricate shaped articles, grinding the brittle materials.

6. Fig 1. Schematic diagram of USM, https://www.mech4study.com/2017/03/ultrasonic-machining-working Fig 2. USM process, https://learnmech.com/working-of-ultrasonic-machining-us/ WORKING PRINCIPLE (3,5)

7. In ultrasonic machining, a tool of desired shape vibrates at an ultrasonic frequency (19 ~ 25 kHz) with an amplitude of around 15 – 50 μm over the workpiece. Generally the tool is pressed downward with a feed force, F . B etween the tool and workpiece, the machining zone is flooded with hard abrasive particles generally in the form of a water based slurry. As the tool vibrates over the workpiece, the abrasive particles act as the indenters and indent both the work material and the tool. The abrasive particles, as they indent, the work material, would remove the same, particularly if the work material is brittle, due to crack initiation, propagation and brittle fracture of the material. Hence, USM is mainly used for machining brittle materials , which are poor conductors of electricity and thus cannot be processed by Electrochemical and Electro-discharge machining .

8. Amplitude of vibration (a) : 15 – 50 μm Frequency of vibration (f) : 19 – 25 kHz Feed force (F) – related to tool dimensions Feed pressure (p) Abrasive size : 15 μm – 150 μm Abrasive material : Al 2 O 3 , SiC , B 4 C Flow strength of work material Flow strength of the tool material Contact area of the tool Volume concentration of abrasive in water slurry PROCESS PARAMETERS (5)

9. MATERIAL REMOVAL MECHANISMS (7) Three well-recognized major removal actions are summarized - Mechanical abrasion due to direct hammering of larger abrasive particles on the workpiece surface. Microchipping resulted from the impact of free-moving abrasive particles. Cavitation erosion from the abrasive slurry. (a) hammering action (b) impact action (c) cavitation erosion Fig 3. https://www.intechopen.com/, Ultrasonic Machining, by Jingsi Wang, 2018

10. Ultrasonic Machining can be used to machine brittle, non-conductive material s , h ard and f ragile material s. Heat is not generated in this machining process. It is burr less and distortion fewer processes. Operation is noiseless. Good surface finish and high accuracy can be achieved. Every material can be machined irrespective of its conductivity. Material Removal Rate is Low. Low penetration rate. The energy requirement for cutting is high. High Tool wear rate due to the movement of abrasive particles. ADVANTAGES (3) LIMITATIONS (3)

11. APPLICATIONS (2) Used for machining hard and brittle metallic alloys, semiconductors, glass, ceramics, carbides etc. Machining very precise and intricate shaped articles . Drilling the round holes of any shape. Grinding the brittle materials. C utting threads in components made of hard metals and alloys Used to cut industrial diamonds. Used for making dies. Fig 5. Machining of advanced materials with enhanced USM, DMG MORI, Finland Fig 4. Complex ceramics products with USM, https://www.mfgnewsweb.com/

12. CONCLUSION (6) USM is of particular interest for the machining of conductive, non - conductive, brittle materials such as engineering ceramics. USM process is purely depends on the work material properties mainly hardness and fracture toughness, tool properties, abrasives properties and process settings. The machining of materials such as Glass, super alloys, tungsten carbide,etc to their final dimensions by conventional methods is extremely tough and generally not possible. To overcome such kinds of problems, USM can be utilized.

13. REFERENCES [1] Non traditional manufacturing processes- Gary.F Benedict , National Library of Australia. [2] https://themechanicalengineering.com/ultrasonic-machining/ [3] https://learnmechanical.com/ultrasonic-machining/ [4] https://www.sciencedirect.com/science/article/pii/S2090447914001476 , Parametric optimization of ultrasonic machining process using gravitational search and fireworks algorithms, by Debkalpa Goswami, Shankar Cakraborty,Department of Production Engineering, Jadavpur University - 2014 [5] https://nptel.ac.in/content/storage2/courses/112105127/pdf/LM-36.pdf , Ultrasonic Machining [6] https://www.slideshare.net/ultrasonic-machining-72691480 [7] https://www.intechopen.com/chapters/59978 , Ultrasonic Machining: A Total Mechanical Machining Technology Using Loose Abrasive Particles by Jingsi Wang, 2018

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